The present invention is directed to an occupant sensing system and an associated method, and is particularly directed to occupant sensing using an image sensor to sense an occupant.
Occupant protection systems are well known in the art and are employed in vehicles to restrain vehicle occupants during a vehicle crash event. Most occupant protection systems include one or more actuatable components, such as an air bag, a seat belt pretensioner, a side curtain, etc. During a crash event, these components may be actuated to physically engage the occupant and restrain the occupant during the crash event.
Deployment or actuation of the actuatable component is usually dependent upon numerous criteria, such as crash conditions and/or occupant characteristics. With respect to crash conditions, a crash condition may be indicated by a crash metric, such as crash acceleration, crash velocity, crash displacement, etc. For example, if a crash metric, such as crash acceleration, is greater than a predetermined threshold crash acceleration value, then this may be regarded as an indication that the crash event is a deployment crash event (e.g. a crash event having a magnitude and/or duration great enough to warrant actuation of the actuatable protection component).
With respect to occupant characteristics, occupant characteristics may include presence, position, and weight of the occupant. Deployment or actuation of the actuatable protection component may be dependent upon occupant characteristics. With reference to an air bag, for example, deploying the air bag is wasteful if an occupant is not present. Also, depending on the size and position of an occupant that is present, deploying the airbag may not provide enhance protection of the occupant. Thus, it may be desirable to suppress actuation. Alternatively, depending on the size and position of an occupant that is present, it may be desirable to only inflate the air bag to a partial amount of the total pressure.
To sense crash conditions, a variety of sensors may be placed at a variety of locations throughout the vehicle. These sensors sense the conditions and output signals indicative thereof. The signals are usually sent to a controller (typically a microprocessor or microcomputer). The controller then uses these signals to control actuation of the actuatable restraining component in a known manner (e.g. by determining whether a crash event is a deployment crash event).
With respect to sensing occupant characteristics, such as the presence of an occupant, several different arrangements and methodologies have been developed to sense these characteristics. For example, imaging technologies have been utilized to acquire an image of the interior of a vehicle to determine the presence and/or position of an occupant.
U.S. Pat. No. 6,005,958 discloses a camera unit that is used to generate image data of the front seating area of the vehicle. Objects and occupants are distinguished through periodic mapping of the image taken by the camera unit. Stored profile data is utilized to determine the occupant or object type.
U.S. Pat. No. 5,531,472 discloses an image sensor that is used to obtain image data which is representative of an occupant on a vehicle seat. The image data is compared to stored image data to obtain the occupant""s size and position within the vehicle.
U.S. Pat. No. 5,528,698 discloses an image sensor that acquires a representation of the passenger seat area within a vehicle. Objects within the field of view of the sensor are discriminated to determine whether a rear facing child seat is located in the passenger seat.
While the related art patents may use an image sensor in the determination of the presence of an occupant, these patents do not account for any ambient lighting conditions which may affect the viewable image of the interior of the vehicle. Such ambient conditions may for example include shadows and/or lighting variations that occur within the interior vehicle. Accordingly, it would be desirable to develop a true presentation of the interior of the vehicle that is devoid of any effects from ambient lighting effects.
The present invention is directed to an occupant sensing system and an associated method and more particularly to an occupant sensing system and an associated method that uses an image sensor to sense the presence of an occupant.
According to one aspect of the present invention, the system includes an illuminating element for selectively illuminating the interior of a vehicle. The system also includes an image sensor for acquiring a first image of the interior of the vehicle when the interior of the vehicle is illuminated by ambient sources only. The image sensor also acquires a second image of the interior of the vehicle when ambient sources and the illuminating element illuminate the interior of the vehicle. A controller is included for removing the effect of ambient sources by comparing the first and second images. The controller thereby produces a third image of the interior of the vehicle as illuminated by the illuminating element only. The controller also determines the presence of an occupant by comparing the third image to a produced map of the interior of the vehicle.
According to another aspect of the present invention, to produce the map, the image sensor acquires a first map of the interior of the vehicle when the interior of the vehicle is illuminated by ambient sources only and acquires a second map of the interior of the vehicle when the interior of the vehicle is illuminated by ambient sources and the illuminating element. The controller removes the effect of ambient sources from the map by comparing the first and second maps thereby producing the map of the interior of the vehicle as illuminated by the illuminating element only.
According to another aspect of the present invention, an aspect of the interior of the vehicle constitutes a background within the third image and the map. The controller determines the presence of an occupant by determining whether a portion of the background visible in the map is not visible in the third image.
According to another aspect of the present invention, a method for sensing an occupant is disclosed. The method includes the steps of acquiring a first image of the interior of the vehicle when the interior of the vehicle is illuminated by ambient sources only and acquiring a second image of the interior of the vehicle when the interior of the vehicle is illuminated by ambient sources and an illuminating element. The method also includes the step of removing the effect of ambient sources by comparing the first and second images thereby producing a third image of the interior of the vehicle as illuminated by the illuminating element only. The method further includes the step of determining the presence of an occupant by comparing the third image to a produced map of the interior of the vehicle.
According to another aspect of the present invention, the method also includes the steps of acquiring a first map of the interior of the vehicle when the interior of the vehicle is illuminated by ambient sources only and acquiring a second map of the interior of the vehicle when the interior of the vehicle is illuminated by ambient sources and the illuminating element. The method also includes the step of removing the effect of ambient sources from the map by comparing the first and second maps thereby producing the map of the interior of the vehicle as illuminated by the illuminating element only.
According to yet another aspect of the present invention, the method further includes the step of determining the presence of an occupant by determining whether a portion of a background visible in the map is not visible in the third image.